Optical Fun

I was recently invited to guest lecture at NDSU to talk about atmospheric optics.  It may sound boring so some, but the interaction of the sun with the atmosphere makes for many displays that we may take for granted. 

For instance, it is the scattering of the violet and blue colors from the incoming solar radiation with the atmosphere that makes the sky look blue (our eyes are more sensitive to blue than violet).  When sunlight strikes the water droplets in a cloud, all the colors tend to be scattered and when our eyes detect all the colors at once, we see that as white. 

Another white object we see in the sky are crepuscular rays, often called sun beams or “Jacob Ladders” as dust and other particulate matter in the atmosphere also tend to scatter all colors.  When the sun in near the horizon, the light must penetrate much more atmosphere to reach our eyes, meaning most of the violets, blues, and greens are all scattered away, leaving us with our beautiful orange and red sunrise and sunsets we often witness.